CHAPTER 3. VOR SYSTEM SECTION 1. OPERATIONAL CHARACTERISTICS FOR VOR GROUND COMPONENTS Paragraph Page
50. Introduction 13
51. Polarization 3
52. Radio Frequency Accuracy 13
53. Signal Strength In Space 13
54. Azimuth Signal Characteristics 13
55. 30 Hz Amplitude Modulation . 14
56. Amplitude Modulation Frequency and Accuracy 14
57. Depth of Reference and Variable Phase Modulations 15
58. Phase Relationship of Reference and Variable Phase Signals
59. Code Identification Signal Characteristics
60. Voice Identification and Communications Signal Characteristics
61. Monitoring 1
62.-79. [Reserved] * * * SECTION 2. OPERATIONAL CHARACTERISTICS FOR VOR AIRBORNE COMPONENTS
80. Introduction
81. Receiver Stability
82. Receiver Sensitivity
83. Rejection of Undesired Signals
84. Mistuning Protection
85. Facility Identification and Voice Signals 16
86. Bearing and Course Deviation Information
88. Course Deviation Display 6
88. Warning Function 6
89. Accuracy of Bearing and Course Deviation Information 7
90. Radiation
91.-109. [Reserved] 17 * * * CHAPTER 4. DME AND TACAN SYSTEMS SECTION 1. OPERATIONAL CHARACTERISTICS FOR DME AND TACAN GROUND COMPONENT
110. Introduction 19
111. Polarization 19
112. Transponder Response to Interrogation Signals 19
113. Interrogation Radio Frequency 19
114. Sensitivity to Interrogation Signals 19
115. On-channel Sensitivity. 19
116. Sensitivity at other Pulse Spacings 20
117. Variation of Sensitivity with Interrogation Loading 20
118. Sensitivity to Adjacent Channel Interrogations 20
119. Transponder Dead Time 20 Page IV
Paragraph page
120. Echo Suppression Dead Time 20
121. Transponder Output Signal Characteristics 20
122. Frequency Stability 20
123. Signal Strength in Space 20
124. Radio Spectrum 21
125. Spurious Radiation 21
126. Pulse Shape 21
127. Pulse Coding 22
128. Pulse Power Variation 22
129. Distance Reply Signals 22
130. Reply Efficiency 22
131. Reply Delay Time
132. Random Pulse Pair Signals
133. DME Components 22
134. TACAN Components 23
135. Pulse Pair Rate . 23
136. Ground Component Range Accuracy 23
137. Code Identification Signal Characteristics 23
138. TACAN Azimuth Signal Characteristics 23
139. Bearing Reference Signals. 25
140. Variable Beariny Signals.. 25
141. Relationships of Reference and Variable Bearing Signals 20
142. Precedence of Pulse Transmissions 26
143. Rejection of Undesired Signals 27
144. Receiver Decoder 27
145. Echo Suppression 27
146. Decoder Discrimination 28
147. Receiver Recovery Time 28
148. Desensitization By CW 28
149. Monitoring 29
150.-169. [Reserved] 29 * * SECTION 2. OPERATIONAL CHARACTERISTICS FOR DME AND TACAN AIRBORNE COMPONENTS.
170. Introduction 29
171. Interrogator Signal Characteristics 29
172. Interrogation Radio Frequencies and Accuracy 29
173. Pulse Characteristics 29
174. Pulse Power Variation 30
175. Pulse Coding . 30
176. Interrogation Signal Repetition Rate 30
177. Variation of Repetition Rate 30
178. Signal Strength in Space 30
179. Radio Spectrum 31
180. Radiation 31
181. Component Functional Capabilities and Performance 31
182. Receiver Radio Frequencies 31
183. Receiver Sensitivity 31 Page V
Paragraph Page
184. Rejection of Undesired Signals 31
185. Distance Information 31
186. Warning Function, Distance 32
187. Accuracy of Distance Information 32
188. Memory Functions 32
189. TACAN Bearing and Course Deviation Information 32
190. Course Deviation Displays 32 191: warning Function, Bearing 32
192. Accuracy of Bearing and Course Deviation Information 32
193.-209. [Reserved] . 32
APPENDICES APPENDIX 1. COVERAGE (16 pages)
1. Radio Propagation
2. Ground Station
3. VOR Coverage 4 . DME/TACAN (UPLINK) Coverage 2
5. DME/TACAN (DOWNLINK) Coverage 2
6. Time Availability ...
Figure 1 Signal Time Availability (1 Page). 4 Figure 2 VOR Signal Strength in Space-Long Range (1 Page) 5 Figure 3 TACAN (RTB-2) Signal Strength In Space-Long Range (1 Page).
Figure 4 Cardion DME Signal Strength In Space-Long Range (1 Page) 7 Figure 5 Cardion DME Signal Strength In Space-Long Range (I Page) 8 Figure 6 Montek DME Signal Strength In Space-Long Range (1 Page) 9 Figure 7 Montek DME Signal Strength In Space-Long Range (I Page). 10 Figure 8 VOR Signal Strength In Space-Short Range (1 Page)... 11 Figure 9 TACAN (RTB-2) Signal Strength In Space-Short Range (1 Page). 12 Figure 10 Cardion DME Signal Strength In Space-Short Range (1 Page). • 13 Figure I1 Cardion DME Signal Strength In Space-Short Range (1 Page). .. 14 Figure 12 Montek DME Signal Strength In Space-Short Range (I Page). .. 15 Figure 13 Montex DME Signal Strength In Space-Short Range (1 Pas.). • 16 Page VI
Page APPENDIX 2. SYSTEM ACCURACY (3 pages) •
1. System Accuracy ...
2. Bearing Error Component Defin tions
3. Error Combination 2
4. Distance Error .. 3 APPENDIX 3. VOR/DME/TACAN CHANNEL FREQUENCIES AND PAIRING (7 pages) APPENDIX 4. DEFINITIONS (2 pages) * * Figure Page 2-1 Standard H (High) Altitude Service Volume 6 2-2 Standard L (Low) Altitude Service Volume 6 2-3 Standard T (Terminal) Service Volume 6 2-4 Definition of the Lower Edge of the Standard
- (Terminal) Service Volume .. 7 2-5 Derinition of the Lower Edge of the Standard H (High) and L (Low) Service Volume 4-1 Random Pulse Distribution Limits 24 * * * Page VII
CHAPTER 1. GENERAL SECTION 1. INTRODUCTION
1. PURPOSE. This order establishes the Very High Frequency Omnidirectional Radio Range (VOR)/Distance Measuring Equipment (DME)/Tactical Air Navigation (TACAN) standard defining the performance required of the system and its components.
2. DISTRIBUTION. This order is distributed to: a) branch level in the
3. CANCELLATION. Order 1010.55, Selection Order: U.S. National Aviation Standard for the VORTAC System, dated 6/1/70 is cancelled.
4. IMPLEMENTATION CRITERIA. The National Aviation Standard applies to all VOR, DME, and TACAN ground and airborne equipments used in the National Airspace System (NAS).
5. DIRECTED ACTION. Subject to applicable rulemaking, programming and budgetary procedures, actions shall be taken by the FAA elements concerned to implement this Standard.
SECTION 2. OVERVIEW
6. GENERAL. Under Public Law 85-726, the Federal Aviation Administration (FAA) is charged with providing for the regulation and promotion of civil for the safe and efficient use of the airspace by both civil and military evaluate systems, procedures, facilities, and devices, defining their performance characteristics as needed. This effort is directed toward meeting the need for safe and efficient navigation and traffic control of all civil and military aviation operating in a common Civil/Military System.
7. THE VOR/DME/TACAN SYSTEM CHARACTERISTICS.
This Standard defines the application and performance characteristics of VOR, DME, and TACAN systems in the United States (U. S.).
For ground and airborne components, the material identifies signal, tunctional, and performance characteristics required to meet operational requirements and to provide compatibility between components of the system.
b. The respective airborne component characteristics for VOR, DME, and TACAN apply in entirety to those components used in aircraft operations
• performed under Instrument Flight Rules (IFR). However, for other aircraft operations the applicability is limited to requirements identified in chapter 3, section 2 and chapter 4, section 2 as essential to prevent impairment of services to other NAS users.
Chap 1 Par I Page 1
AC 00-31A 9/20/82./ In all cases, where a parameter and associated tolerance is identified herein, ground stations shall be maintained within these limits of quality assurance methods including either monitoring, periodic ground or flight inspections, or a combination of these methods.
d. Operators of airborne systems designed, installed, and operated in accordance with the Standard can expect to achieve the system performance which the standard is intended to provide.
e. It is recognized that certain existing components do not comply with all requirements of this Standard. Specific characteristics that are known to deviate from the requirements of this Standard will be corrected or replaced as practical.
8. REVISIONS. This Standard will be revised as the needs of the National Airspace System warrant.
9. RELIABILITY REQUIRED OF THE VOR/DME/TACAN SYSTEM. Due to the critical nature of the radionavigation service, it is essential that the VOR/DME/TACAN system provide high reliability. Both signal strength and frequency protection are provided on a basis of 95 percent time availability at the worst case points of the service volume. At other than worst case points, time availability substantially exceeds 95 percent. (See Appendix 1, paragraph 6.)
10.-19. RESERVED.
Chap 1 Page 2 Par 7
CHAPTER 2. VOR/DME/TACAN SYSTEM
20. VOR/DME/TACAN SYSTEM DESCRIPTION. The VOR/OME/TACAN system is a short distance air navigation system. The ground components provide properly equipped aircraft with bearing, identification, and distance information referenced to the selected ground component. When the airtorne equipment includes a suitable area navigation (RNAV) device operating from data derived from the system, both radial and non-radial routes are afforded. The system provides navigation signals to all civil and military aviation for the safe and efficient conduct of aircraft operations, exercise of air traffic control, and use of airspace.
21. GROUND COMPONENTS. The principal ground components are VOR, DME, and TACAN. VOR and DME are the International Civil Aviation Organization (ICAO) standard navigational aids. VOR provides azimuth information and ground-to-air communications for the common NAS. DME provides distance information to all users of the NAS. TACAN provides azimuth information primarily to military users and distance information to all users of the NAS.
STATION TYPE DESIGNATIONS. Ground components are identified by type designations which indicate the service provided. VoR type designations are prefixed by the letter "B" when the component provides scheduled voice broadcasts. The letter "W" is used when the component does not provide voice transmissions.
Designation Iype of Facility VOR VHF navigation facility, omni-directional azimuth only DME UHF navigation facility, distance only TACAN UHF navigational facility, omni-directional, azimuth and distance VOR / DME Associated VOR and DME navigational facilities VORTAC Associated VOR and TACAN navigational facilities SERVICE VOLUMES. Maximum usable range is influenced by a large number of variables. These include factors such as antenna patterns, propagation variation, ground terrain, ground and avionics equipment performance; ground and avionics equipment installation and maintenance, traffic loading and traffic distribution. It should be noted that the aviation community has many years of operational experience with the VOR/DME/TACAN system. Service volumes are predicated on both experience and empirical measurements.
Chap 2 Par 20 Page 3
9/20/82 surficient safety margin has been incorporated, to assure highly reliable system operation. Under worst case conditions, it is recognized that some combinations of avionics and older ground equipments may not provide service with a time availability of 95 percent. Based on operational experience and user feedback, no substantial evidence indicating an adverse operational impact has been shown. In addition, all service volumes are flight inspected prior to commissioning for operational use. Nonetheless, ground and airborne equipment should be brought into full compliance with this National Aviation Standard as soon as it is practical.
a. Standard Service Volumes (SSV).
(1) Ground stations are classified according to their intended These stations are available for use within their service volume.
Outside the service volume, reliable service may not be available.
standard use, the airspace boundaries are called standard service volumes.
They are defined, in the table below, for the three station classes.
SSV CLASS
DESIGNATOR ALTITUDE AND RANGE BOUNDARIES T (Terminal) From 1000 feet (305 m) AGL up to and including 12,000 feet (3,658 m) AGL at radial distances out to 25 nmi (46 km). See Figures 2-3 and 2-4.
L (Low Altitude) From 1000 feet (305 m) AGL up to and including 18,000 feet (5,486 m) AGL at radial distances out to 40 nmi (74 km). See Figures 2-2 and 2-5.
H (High Altitude) From 1000 feet (305 m) AGL up to and including 14,500 feet (4,420 m) AGL at radial distances out to 40 nmi (74 ‹m). See Figures 2-1 and 2-5. Fron 14,500 feet (4,420 m) AGL up to anc including 60,000 teet (18,280 m) at radial distances out to 100 nmi (185 See Figures 2-l and 2-5.
18,000 feet (5,486 m) AGL up to and including 45,000 feet (13,716 m) at radial distances out to 130 nmi km). See Figures 2-l and 2-5.
(2) These SSV's are graphically shown in Figures 2-1 through 2-5.
The SSV of a station is indicated by using the class designator as a prefix to the station type designation. (Examples: TVOR, LDME, and HVORTAC.)
Chap 2 Page 4 Par 23
Within 25 nmi (46 km), the bottom of the i Service is defined by the curve in Figure 2-4. Within 40 nmi (74 km), the bottoms of the L and H service volumes are defined by the curve in Figure 2-5. In some cases, local conditions (terrain, buildings, trees, etc.) may require that the standard service volume be restricted. The public shall be informed of any such restriction by a Notice to Airman (NOTAM).
NOTE: Metric measurements are given for convenience and are approximations.
b. Expanded Service Volumes. When operational needs require facilities to be used beyond their standard service volumes, the same signal standards/tolerances and ground/flight check certification procedures will be met. Expanded service volumes (ESVs) will only be authorized when conditions permit (reference Figures 2 through 13 of Appendix 1.).
c. Operational Service Volume. The airspace available for operational use includes:
(1) The SSV excluding any portion of the SSV which has been restricted, and
(2) expanded service volumes (ESVS).
d. Vertical Angle Coverage Limitations. Within the operational service volume of each station, azimuth signal information permitting satisfactory performance of airborne components is normally provided from the radio horizon up to an elevation angle of approximately 60 degrees for VOR components and approximately 40 degrees for TACAN components. At higher elevation angles, the azimuth signal information may not be usable. Distance information provided by DME and TACAN will permit satisfactory performance of airborne components from the radio horizon to an elevation angle of not less than 60 degrees.
24. ASSOCIATED COMPONENTS. A VOR and either a DME or TACAN shall be considered as associated components only when:
a. operated on a standard frequency pairing as associated with paragraph 28;
b. collocated as defined in paragraph 25; and
c. complying with the identification provisions of paragraph 32.
25. COLLOCATION LIMITS FOR ASSOCIATED COMPONENTS. OME or TACAN components are frequency-paired with VOR. For the common system, these components shall be collocated in accordance with one of the following.
a. Coaxial collocation. The VOR and DME or TACAN antenna are located on the same vertical axis. This is the usual collocation configuration.
Chap 2 Par 23 Page 5
FIGURE 2-1. STANDARD HIGH
ALTITUDE SERVICE VOLUME (refer to FIGURE 5 for altitudes below 1000 feet (305 m) 100 nmi (185 km) 80,000 fr (18,288 m) 130 nmi (241 km) 45,000 r (13,716 m) 18,000 K.
(5,486 m.)
14,500 ft (4,420 m) FIGURE 2-2. STANDARD LOW 1,000 ft. 40 nmi ALTITUDE SERVICE VOLUME (305 m) (74 km) (refer to FIGURE 5 for altitudes balow 1000 feat (305 m) 40 nmi (74 km) 18,000 ft.
(5,486 m) FIGURE 2-3. STANDARD TERMINAL SERVICE VOLUME 1,000 ft.
(refer to FIGURE 4 for altitudes - (305 ml below 1000 feet (305 m) 25 nmi (46 km) 12,000 ft. NOTE: All elevations shown are with respact (3,658 m) to the station's site elevation (AGL).
Metric Measurements are given for convenience and are approximations.
These figures do not reference the aria defined as the Vertical Angle Coversge Limitations (paragraph 23d.)
1,000 fr (305 m) Page 6
FIGURE 24. DEFINITION OF THE LOWER EDGE OF THE STANDARD T (TERMINAL) SERVICE VOLUME 1002 - 300
- 250 ALTITUDE IN METERS ALTITUDE IN FEET - 200 500- 150 50 10 15 20 DISTANCE TO THE STATION IN mi
T T T en • 10 15 20 25 30 35 40 45 DISTANCE TO THE STATION IN km FIGURE 25. DEFINITION OF THE LOWER EDGE OF THE STANDARD H (HIGH) AND L (LOW) SERVICE VOLUMES 1000 - 300 250 ALTITUDE IN METERS ALTITUDE IN FEET • 200 500 15
• 100 50 a- 10 15 20 25 30 35 40 DISTANCE TO THE STATION IN nmi
T T T 10 DISTANCE TO THE STATION IN KM 60 70 80 Page 7
b. Offset collocation.
(1) For those facilities used in terminal areas for approach purposes or other procedures where the highest position fixing accuracy of system capability is required, the separation of the VOk and UMt or lALAN antennas will not exceed 100 feet (30 m). However, at Doppler voR sites the antennas may be separated by not more than 260 feet (80 m).
(2) For purposes other than those indicated in (1), the separation of the VOR and either the DME or TACAN antennas will not exceed 2000 feet (610
m) .
26. RADIO FREQUENCY ALLOCATIONS. Radio frequencies allocated for VOR, DME, and TACAN are those listed in Appendix 3.
27. RADIO FREQUENCY ASSIGNMENTS. Radio frequency assignments for the paired system components shall be selected from the frequency pairings listed in Appendix 3. Channels I through 16 and 60 through 69 for both X and Y modes of operation shall not be assigned to components of the common system.
28. RADIO FREQUENCY CHANNEL PAIRING. Appendix 3 shows the pairing of the VHF and UHF components of the VOR/DME/TACAN System. Components associated according to paragraph 24 shall be assigned on paired frequencies in accordance with this table. Non-associated VOR, DME, and TACAN components shall not be assigned on paired frequencies unless the separation between the respective components is sufficient to satisfy paragraph 29. This latter separation shall be determined as if each station was in effect an associated frequency pair.
29. FREQUENCY INTERFERENCE PROTECTION. Frequency assignments must not result in interference between stations. Within a station's operational service olume, the ratio or the desired signal to any undesired signal must not tal below te selection/rejection capability of the airborne equipment.
Paragraphs 29.a through 29.c discuss interference protection needed. The usable distance and altitude of aeronautical navigation aids are often limited by the frequency protection provided from other ground stations. The operational service volume shall not extend beyond the frequency protected service volume.
a. Interference Protection of VHF NAVAIDS ILS and VOR). The following interference signal protection ratios shall be provided within the operational service volume of all Instrument Landing Syatem (ILS) and VOR stations with a 95 percent time availability. This is done by controlling the station separation in certain situations.
(1) The desired to undesired (D/U) signal ratio between co-channel stations shall not be less than +20 dB.
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